The present invention relates to a pneumatic tire, more particularly to a configuration of tread grooves for a heavy duty tire capable of improving resistance to shoulder wear of the tread portion and wet performance in the early period of the tread wear lifetime.
Heavy duty tires such as mud and snow tires and all terrain tires for use on rough terrains are usually provided with block-type tread patterns constituted by independent blocks separated from each other by deep tread grooves. On the other hand, heavy duty tires such as truck-and-bus tires for use on well-paved roads are usually provided with rib-type tread patterns constituted by circumferentially continuous ribs because the ribs can withstand heavier tire loads than the blocks. Even so, the heavy duty tires with rib-type tread patterns are liable to suffer from so called shoulder wear resulting from their relatively round tread profiles and heavy tire loads. Especially, the shoulder wear is liable to occur on the steered front wheels because a larger frictional energy is applied to the tread shoulder portions due to front wheel alignments, steering movements of the front wheels, relatively light tire load when compared with rear tires and the like.